This invention relates to apparatus and devices for cutting vegetation and the like, and more particularly relates to improved apparatus for cutting vegetation with a flexible non-metallic cord member.
It is well known to cut or mow grass, weeds and other vegetation with a moving flail-like member, and it is now well known to employ a flexible non-metallic cord member for the purpose of cutting vegetation located in places which are inaccessible to apparatus employing a rigid steel blade. In particular, the trimmer which is marketed in various forms under the trademark WEED EATER, and which is described in U.S. Pat. Nos. 3,708,967; 3,826,068; and 3,859,776; is now widely known and used for this purpose.
This invention relates to an improved cutting assembly in the form of a rotary head for a rotary edger, trimmer or the like. The preferred embodiment is in the form of a portable type mowing and edging tool wherein the cutting element is safe in most uses and avoids the hazardous conditions created by prior art devices.
The prior art is prolix with attempts at solutions to provide a safe, efficient and simply constructed rotary head for rotary mowers, edgers, trimmers and the like. One attempt comprises a rotating metal bar or the like which is rotated at sufficient speeds to effect cutting of grass, weeds or the like. However, such bars create hazardous conditions in that when they strike certain objects they act upon those objects in a fashion to create and project dangerous missiles which may strike the operator or individuals in the area of work.
Various attempts have been made to overcome the aforesaid hazardous conditions created with rigid-type metal cutting blades of the prior art. Most of these attempts to overcome the problem involve the utilization of some type of flexible flail which will have sufficient resiliency so as not to propel objects which are struck at high velocities. Most of these resilient type cutting elements of the prior art suffer a disadvantage in that they are not safe and mere resiliency is not sufficient to insure that the dangerous conditions will not be created when rotation is effected at desired cutting speeds. Further, the prior art cutting elements are generally not provided with means for easy replaceability in the event of wearing out and are usually expensive to replace.
The result has been that most of the prior lawn and edging apparatus have been unsatisfactory because of the dangerous conditions created by the rotating head. As a consequence, most lawn edging and trimming around trees and the like, which would otherwise be damaged by the metal blades, must be done manually, which is both laborious and time consuming.
There is depicted and described in the following West German Petty Pat. Nos. 6,919,841; 6,919,842; 6,919,843; 6,919,844; 6,938,265; 7,043,648 and 7,238,972, one or more embodiments of a lawn mowing or trimming device having a disc-like head member arranged to be rotated by a motor, and containing a spool which is housed therein in coaxial relationship to the shaft of the motor. A length of flexible non-metallic line is coiled about the spool, whereby its free travelling end extends generally peripherally from the spool and head, and whereby such free travelling end will be swung arcuately about upon actuation of the motor to cut adjacent vegetation in the manner of a flail.
The German device will cut effectively only lightweight vegetation and suffers severely from a high-breakage rate of the plastic line.
These disadvantages of the prior art, and especially the aforementioned German device, are overcome with the present invention, and a commercially acceptable embodiment of a vegetation cutter and the like is herein provided which is not only fully capable of cutting vegetation under most operating conditions, but which is also fully capable of other tasks completely beyond the capabilities of the German device, such as cleaning dead leaves, trash and other such debris from along fences, walls and the trunks or stems of trees and bushes. More particularly, however, the embodiment of the present invention is capable of operation with a much higher efficiency and much lower lower breakage rate for its cutting strings.